Envelope window patching

ABSTRACT

A hot melt coating on a window patch is softened and adhered in place on a blank window for a a windowed container such as a window or the like using one or more hot rolls nipped against a cooled vacuum roll which holds the window and blank in place relative to each other. This system can also be applied to patching webs from which window envelopes can be cut.

I United States Patent 1191 1111 3,887,414 Cohn June 3, 1975 [54]ENVELOPE WINDOW PATCHING 2,257,829 10/1941 Winkler et al. 93/61 A2,794,485 6/1957 Ashton et al. 156/282 [75] Invent: 00h", Mllbrae Cahf-3,416,414 12/1968 Smithe 156/521 [73] I Assignee: Champion InternationalCorporanon, Hamllton Primary Examiner-Daniel .l. Fritsch 2 Filed; Man 21973 Atgorieyl, Agent, or FirmGardiner, Sixbey, Bradford an ar son [2]]Appl. No.: 345,165

[52 US. Cl. 156/108; 93/61 A; 156/256; ABSTRACT [51] i g 156/498;156/514; 15 1 63; A hot' melt coating on a window patch is softened and58] i 2 6 4 282 adhered in place on a blank window for a a windowed152/498 62 container such as a window or the like using one or 63 morehot rolls nipped against a cooled vacuum roll which holds the window andblank in place relative to each other. This system canalso be applied topatch- [56] :Z" ing webs from which window envelopes can be cut.

2,072,875 3/1937 Gray 93/61 A 7 Claims, 5 Drawing Figures ENVELOPEWINDOW PATCHING.

BACKGROUND AND SUMMARY'OF'THE l INVENTION 1 This invention relates toimprovements in a method and apparatus for applying a window patch to ablank or web from which can be made a windowed container such as awindow envelope. One aspect of the invention is to use a vacuum to holdthe patch and web or container blank in position relative to each other.An aspect of the invention is to use all rotary means such as a vacuumdrum and a rotary heated roll in combination, in connection with whichthe same will be described for applying a patch to an envelope blank byway of example, it being understood that other applications of theinvention such as to webs from which blanks for forming into containersof various types are to be cut are contemplated and embraced herein.Thus the invention is limited only to the extent that the containerstock or blanks must be flexible enough to respond readily to thevarious manipulative acts or steps comprising the hereinafter describedmethod.

The prior art knows to use vacuum rolls or drums as a means to feedenvelope blanks or the like through equipment for gumming and formingthem into a finished envelope. Vacuum has also been employed inconnection with the manufacture of window envelopes. There are specialproblems in making window envelopes because if the adhesive for holdingthe patch over the window runs out and down the front of the window itwill tend to stick to the adjacent envelope and at least look unsightly.If the adhesive runs out from under the patch inside the envelope thenthe front and back panels of same are stuck together which isunsatisfactory.

The 1937 US. Pat. No. 2,072,875 to Gray teaches using a source of vacuumto hold an envelope and a window patch therefor in relative positionwhile applying heat sufficient to melt a hot melt adhesive coated on thepatch to the adhering point. Reciprocating members are taught by Gray.Moreover, this patent teaches using a concave surface to support theblankpatch combination (the window portion of the patch is supported insaid concavity out of conductive heat contact with the heating surface),during the application of heat and thereby requires precise placement ofhis work pieces relative to the concavity. At the same time the Grayapparatus utilizes reciprocating members with all of the disadvantagesof the slow vibrating type of operation realized with reciprocatingmembers.

The present invention provides an advance over Gray in that a completelyrotary system is provided whereby smoother and faster running isachieved. Moreover, a cylindrical vacuum drum is used to hold the blankand patch in register with each other during the time heat is applied.The convex surface of the drum acts as a support for the blank-patchassembly.

Although the blank and patch are placed carefully relative to eachother, it is unnecessary to precisely place the blank and patch relativeto the drum, as with Gray and his concavesupport. However, the patch ispulled into the window of the blank to thus be spaced away from the heatsource and to avoid sticking to the vacuum roll.

. Y The present invention has consistently produced windowed containerswhere the windows are adhered right up to the edge of the hole in theenvelope blank on the outside and are adhered right up to the edge ofthe patch on the inside of the container. Such a resulting otherenvelopes, machine elements) on the outside or of hooking inserts on theenvelope inside, respectively, if the patch is not adhered to the edgesof the window or of the patch to leave loose, free marginal edges whichcan hook such other objects.

Additional features and advantages will become apparent from thefollowing description when read in connection with the drawings wherein:

FIG. 1 is a schematic side view of a patch applying machine showing therotating elements of the invention;

FIG. 2 is a view of an envelope blank and window patch as seen from theinside of the envelope;

FIG. 3 is an isometric view of an assembled envelope with a window patchin place;

FIG. 4 is a schematic axial view along 4 4 of FIG. 1; and

FIG. 5 schematically shows details of one embodiment of a patch feedingmeans and cooled vacuum roll as used with and/or in the FIG. 1 assembly.

As seen in FIGS. 2 and 3, the well-known window envelope used as anexample of one product to which the invention pertains, comprisesbasically three elements an envelope blank 1 folded in an appropriatefashion, a window patch 2 and adhesive 3 to hold the patch on the blank.The patch obviously is secured in place in register and over the window4 on the envelope. Although some window envelopes are made without apatch, they are not germane to this invention.

In the present invention, the window patch 2 has for an adhesive 3 acoating of hot melted adhesive, preferably formed from Elvax eitheralone or extended by various waxes, microcrystalline waxes, and similardilutants. Elvax is the trademark for a vinyl resin copolymer made by E.I. duPont de Neumours and Company which broadly speaking is a copolymerof ethylene and vinyl acetate. A preferred hot melt formulation consistsin 30 percent by weight of either of the grades of Elvax mixedthoroughly with about 70 percent by weight of paraffin wax. Alternativehot melt mixtures can be formulated in any of the known manners. Athorough discussion of the 30/70 formulation, other formulae, and usesfor Elvax is found in the July, 1961 Modern Packaging, pages 134 et seq.

Alternative mixtures may include other waxes and polymers, anti-oxidant,anti-scorching or clarity preservers, or release agents.

The preferred hot melt adhesive has a softening point in the range fromabout 250 to about 300 F. and is applied to the window patch material byconventional equipment prior to the instant patching operation.

The window patch for such an envelope by way of example is of a materialthat is selected from the group comprising or consisting of transparentand translucent adherable films and webs capable of withstanding the,

high temperature of about 425 F. to which it is subjected momentarily.For many years glassine has been preferred for windows despite itstendency to be translucent and it is still preferred because it canwithstand the high temperature (about 425 F.) which it is subjected towith the Elvax heat. Most plastic films such as polystyrene, cellulose,and the like will soften, wrinkle, or even stick to the equipment ifsubjected to such temperatures. However, Mylar (polyethyleneterephthalate) film can also be used at these temperatures with theElvax hot melt adhesive and also is preferred material especially wheretransparency is desired as a prime consideration. The envelope blank ismade of ordinary envelope paper which is a sized uncoated grade ofquality paper and which is of such basis weight as to be flexible enoughto permit of the manipulative steps of the method, as must be any basestock or blank employed in the operations to be subsequently describedin greater detail.

The apparatus according to the present invention (FIGS. 1,4) comprises awater cooled vacuum drum 5 which is supported on a frame 6 (that isbetween the side frames 6) to rotate substantially adjacent to a heatedroll 8 which is also supported on the frame 6.

Vacuum drums and their construction are old and well known in theenvelope making art. Vacuum drum 5 is a hollow cylindrical shellvAs bestseen in FIG. 5 the drum comprises a cylindrical shell having a pluralityof radially extending vacuum ports 9 arranged around its face. Shell 10is preferably of aluminum. Formed within the wall of the shell are aplurality of vacuum passages 11 each of which is connected to a numberof the ports 9. The drum is, as is conventional, connected by suitablemeans such as a rotary coupling or shaft seal to a suitable vacuumsource such as a vacuum pump, steam jet ejector, or the like. The vacuumestablished through ports 9 are employed to hold the blank and the patchon the drum in register with each other from the time of depositing thepatch in register over the window within the nip between vacuum roll 5and the vacuum transfer roll 12. In some cases it may be necessary toprovide additional Heating and/or auxiliary cooling, This may readily beaccomplished as by providing a supplemental heating or cooling roll 15.However, on most occasions, the roll 15 will not be needed and for thisreason is shown in dotted lines on FIG. 5.

The interior of the drum 5 is connected by appropriate means such astubing, a hollow shaft, and rotary coupling or shaft seal to a source ofcooling fluid, preferably cooling water. By use of this cooling system,the convex surface of the drum is kept cool enough so that the adhesiveon the window of the envelope wont stick to the surface, scorching ofthe blank is prevented, clouding or blooming of the window patch and/orits coating is reduced, and cooling is accelerated once the hot melt hasbeen activated by the heat from roll 8.

The blank feeding means illustrated in FIG. 5 is the preferredembodiment although various other types of patch feeders could beemployed. Basically, this involves a system for unwinding a web of patchmaterial, such as glassine or Mylar, directing it against a knife orother cutting means where individual patches are severed, and then usingthe vacuum transfer roll 12 to feed the patch to the envelope blank. Thesystem is coordinated with the feeding of the individual blanks or a webcontaining a series of blanks so that the patch arrives means of a pairof draw rolls 17. The draw rolls form a nip or turning couple and arepressed against each other hard enough that they firmly engagethe patchmaterial 2A, unwinding it from the roll or reel 2A, and feeding it to arotary knife 18 which cooperates with a stationary knife 19 to severindividual window patches from the web. Each patch 2 is severed at thetime enough of it has fed past the rotaryknife I8, 19 to form a windowat which time it engages the vacuum transfer roll 12 which is anordinary vacuum roll of the sort well known in the envelope machineindustry.

The vacuum rolls 5 and 12 are of conventional construction so far as thevacuum portions are concerned. They use rotary shaft seals and couplingsas already mentioned for the feeding of air through the vacuum passagesto a vacuum pump or the like. The various vacuum ports 9 in both rollsare turned on and shut off in a predetermined timed sequence controlledby valve plates or some other conventional timing device which need notbe belabored further at this point.

For example, parts A in the vacuum drum 5 (FIG. 5) are turned on as theyreach the position A which is where the envelope blank is first fed tothe drum. These ports stay on, pulling a vacuum through them and therebyretaining the blank thereon until after all the operations of affixingthe window have been completed. The envelope blank with window is, aftercompleting such operations, removed from the drum 5 at a position Ewhere the ports 9 are turned off to free the windowed blank for such asare required subsequent operations complete the gumming, flap folding,etc.

The vacuum transfer roll 12 has its ports turned on at approximatelyposition F so that a severed window patch can be received from the knife18, 19, retained on the blank for a time sufficient to seat it ortransfer it down to the position B where it is brought into the nipbetween the two vacuum rolls 5, l2 and placed in register on theenvelope window. At the position B the vacuum through the ports of thevacuum transfer roll 12, is shut off since this roll has completed itsfunction of transferring the window patch. Release of the patch by thedrum 12 and its retention by the vacuum existing through ports 9 on thewater cooled drum surface 10 is thus affected. The vacuum remains turnedoff on the ports of the vacuum roll 12 for the time it takes to travel(rotate) from position B to position F and then is on for the rotationfrom F to B.

As indicated previously, the construction of vacuum drums and theircontrol means is well known in the art. Typical vacuum passagemanifolding and control means comprising a valving disc are taught inU.S. Pat. No. 3,457,696 and the references cited therein to that effectsuch as Skow U.S. Pat. Nos. 2,853,296 and 2,635,538. Inasmuch as thedetails of these constructions are well known in the art, it is notdeemed necessary at this time to repeat them.

Returning to the description of the valve timing for vacuum roll 5,vacuum is turned on as the ports 9 reach point A, remains on at the nipB where the patch is received and continues on until the point C atwhich time heat is applied from the heated roll 8. If supplementalheating or cooling is needed, of course, the vacuum stays on duringthose functions whether it is prior to or after the heated roll 8. Forexample, if additional cooling or heating is required by a supplementalroll 15, the vacuum through ports 9 is kept on at least while the portspass the position D and until the ports have reached the position Ewhere the vacuum, by a suitable control means such as the valve platesmentioned in the abovementioned references, is turned off and theenvelope with its now affixed patch is released for manipulation throughthe remainder of the. envelope manufacturing functions.

It will, therefore, be observed that the process for applying a windowpatch 3 to an envelope or web blank having a window cut out comprisesthe steps of feeding a strip 2A of hot melt coated transparent ortranslucent window patch material; severing a patch 2 from said strip bycutting off a predetermined length of it with a rotary knife 18;meanwhile feeding the envelope blank 1 to the rotating cooled vacuumdrum 5 and securing same on the surface thereof by vacuum means;depositing at position B the patch 2 over the window 4 in the blank andholding it in place there by the vacuum drawn through the ports 9 in thevacuum roll, thereby pulling the patch down into the window opening(e.g. FIG. 1); and then moving the blank with the patch on it on thedrum surface (where it is held immovably) through at nip at position Cformed by rotating the drum 5 against a rotating heated roll 8 wherebythe hot melt coating 3 is softened sufficiently to adhere the patch tothe blank. Similarly where a web is used instead of an individualenvelope blank.

In the present invention, it is important that the patch be on theoutside or top of the envelope window as shown in FIGS. 2 and 3 becausethe vacuum roll 5 is thereby enabled to suck the patch down into thewindow 4 and actually out of contact with the heated roll 8 except forthe border of the patch which overlies the areas immediately adjacentthe marginal edges of the window to which the patch is ultimatelyadhered. This feature thereby reduces the amount of heat transferredbetween the heated roll 8 and the window portion of the patch while atthe same time, due in part to the increased thickness of the patch whereit overlies the envelope blank around the window, heat is applieddirectly to the patch and to the envelope thereby achieving therequisite adhesion by means of melting the hot melt adhesive.

It is important that cooling take place on the nonadhering surfaces(i.e. against the drum face 10), not only during, but immediately afterthe activation at C of the hot melt adhesive and any other heating step.First, scorching and other discoloration of both the envelope and theblank are thereby minimized and in most instances eliminated. Secondly,quick cooling assures that the adhesion process is rapidly completed andreduces or eliminates the opportunity for the patch to be moved out ofregister with the window or the like.

The heated roll 8 is preferably electrically heated and has an outercylindrical surface made of aluminum. However, a heated ceramic roll mayon some occasions be selected as conditions may dictate.

Thepressure with which the heated roll 8 is urged against the vacuumroll is also extremely important. A heavy pressure is desired. Where theheated roll is merely swung freely on arms or brackets 22, thereordinarily would not be enough pressure along the line of contact in thenip C to achieve the desired amount of heat transfer and adhesion.Therefore, some sort of positive pressure inducing means such as acounterweight 23 on the mounting arm 22A should be used if the weight ofthe roll itself will not produce the desired pressure. Too, as isobvious. various other pressure applying means, such as springs, aircylinders, etc., may readily be employed to produce the desired results.

Artificial cooling of the drum 5 to lower the temperaturevof surface 10is preferred. However, where operating temperatures are low it ispossible on some occasions to cool the drum surface 10 with either orboth internal and/or external streams of air (e.g. compressed air) andin some instances to eliminate artificial cooling altogether.

By the term artificial cooling is meant intentionally supplying acooling medium in addition to that resulting from natural forces such asconduction, convection, and/or radiation resulting from conditions ofoperation (e.g. rotational speed, surface temperature) and ambientconditions (eg room temperature).

The above machinery may be driven by an electrical motor which isconnected by a suitable transmission to the various drums and rollers.Belt or chain drives are preferred as the most uncomplicated drive meansbecause one motor can be connected to drive and set up and keep thevarious timed relationships between the moving elements with relativeease.

The invention claimed is:

1. A process of applying a window patch to a container blank such as anenvelope or web for formation into a window container and having awindow cut out comprising the steps of A. Feeding a strip of hot meltcoated transparent or translucent window patch material;

B. Severing a patch from said strip by cutting off a predeterminedlength of it; I

C. Feeding said blank or web material to a rotating cooled vacuum drumwith a cylindrical outer surface and securing it uniformly over itsentire surface area by vacuum to said cylindrical surface of said drum;

D. Depositing said patch over the window cut out area in said blank orweb and holding it in place uniformly over its entire surface areawithin the marginal confines of said window cut out by vacuum therebypulling the patch down in its free area into the window opening; whileleaving the marginal edges of the patch overlying the marginal edgeareas circumscribing the window cutout area; and

E. Moving said blank or web with the patch on it on said drum convexsurface through a nip formed by rotating said drum against a rotatingheated roll so that the heated roll contacts only the overlappedmarginal edges of said patch and said blank or web circumscribing saidwindow cut out whereby the hot melt adhesive is softened sufficiently toadhere said patch to said blank only in said overlapped areas.

2. A process of applying a window patch according to claim 1 wherein thestep of feeding comprises the feeding of a strip of hot melt coatedtransparent polyethylene terephlhalate film to subsequently define awindow patch applied to said blank or web.

3. A process of applying a window patch according to claim 1 whereinsaid step of feeding further comprises the feeding of a strip of hotmelt coated transparent glassine to subsequently define a window patchapplied to said blank or web.

4. A process according to claim 1 including the further step ofartificially cooling the vacuum drum.

5. A process according to claim 4 wherein said step of cooling includessupplying cooling water to the drum interior.

6. Apparatus for applying by heat sealing a window patch to a stockmaterial having a window cut out area therein, such as an envelope blankor the like comprisa rotatable, cylindrical, hollow drum having aplurality of suction holes dispersed uniformly throughout at least aportion of its cylindrical surface to hold the windowed web or blankstock material in position on the drum surface throughout its entirearea; means to cool the drum by a cooling fluid passing through theinterior of said drum, and

means to create a vacuum through said suction holes;

rotary means to feed a window patch to and deposit it on the windowedweb or blank material in register with the window cut out therein, saidpatch being held in position throughout its entire surface area withinthe marginal confines of said window cut out by vacuum drawn throughsaid suction holes, and with its marginal edges overlying the marginalareas of said stock material circumscribing said out out; and

a heated cylindrical roll rotatably supported with its cylindricalsurface adjacent the cylindrical surface of said drum which carries saidblank and said patch, so that the heated roll contacts only theoverlapped marginal edge areas of said patch and said stock materialcircumscribing said window cut out.

7. Apparatus for applying a window patch to a stock material all asdefined in Claim 6, wherein said rotary means to feed a window patchincludes rotary means to withdraw a web of patch material from a rollsource thereof and means to sever individual patches from said web priorto positioning of said individual patches against the stock material.

1. A process of applying a window patch to a container blank such as anenvelope or web for formation into a window container and having awindow cut out comprising the steps of A. Feeding a strip of hot meltcoated transparent or translucent window patch material; B. Severing apatch from said strip by cutting off a predetermiNed length of it; C.Feeding said blank or web material to a rotating cooled vacuum drum witha cylindrical outer surface and securing it uniformly over its entiresurface area by vacuum to said cylindrical surface of said drum; D.Depositing said patch over the window cut out area in said blank or weband holding it in place uniformly over its entire surface area withinthe marginal confines of said window cut out by vacuum thereby pullingthe patch down in its free area into the window opening; while leavingthe marginal edges of the patch overlying the marginal edge areascircumscribing the window cut out area; and E. Moving said blank or webwith the patch on it on said drum convex surface through a nip formed byrotating said drum against a rotating heated roll so that the heatedroll contacts only the overlapped marginal edges of said patch and saidblank or web circumscribing said window cut out whereby the hot meltadhesive is softened sufficiently to adhere said patch to said blankonly in said overlapped areas.
 1. A process of applying a window patchto a container blank such as an envelope or web for formation into awindow container and having a window cut out comprising the steps of A.Feeding a strip of hot melt coated transparent or translucent windowpatch material; B. Severing a patch from said strip by cutting off apredetermiNed length of it; C. Feeding said blank or web material to arotating cooled vacuum drum with a cylindrical outer surface andsecuring it uniformly over its entire surface area by vacuum to saidcylindrical surface of said drum; D. Depositing said patch over thewindow cut out area in said blank or web and holding it in placeuniformly over its entire surface area within the marginal confines ofsaid window cut out by vacuum thereby pulling the patch down in its freearea into the window opening; while leaving the marginal edges of thepatch overlying the marginal edge areas circumscribing the window cutout area; and E. Moving said blank or web with the patch on it on saiddrum convex surface through a nip formed by rotating said drum against arotating heated roll so that the heated roll contacts only theoverlapped marginal edges of said patch and said blank or webcircumscribing said window cut out whereby the hot melt adhesive issoftened sufficiently to adhere said patch to said blank only in saidoverlapped areas.
 2. A process of applying a window patch according toclaim 1 wherein the step of feeding comprises the feeding of a strip ofhot melt coated transparent polyethylene terephlhalate film tosubsequently define a window patch applied to said blank or web.
 3. Aprocess of applying a window patch according to claim 1 wherein saidstep of feeding further comprises the feeding of a strip of hot meltcoated transparent glassine to subsequently define a window patchapplied to said blank or web.
 4. A process according to claim 1including the further step of artificially cooling the vacuum drum.
 5. Aprocess according to claim 4 wherein said step of cooling includessupplying cooling water to the drum interior.
 6. Apparatus for applyingby heat sealing a window patch to a stock material having a window cutout area therein, such as an envelope blank or the like comprising arotatable, cylindrical, hollow drum having a plurality of suction holesdispersed uniformly throughout at least a portion of its cylindricalsurface to hold the windowed web or blank stock material in position onthe drum surface throughout its entire area; means to cool the drum by acooling fluid passing through the interior of said drum, and means tocreate a vacuum through said suction holes; rotary means to feed awindow patch to and deposit it on the windowed web or blank material inregister with the window cut out therein, said patch being held inposition throughout its entire surface area within the marginal confinesof said window cut out by vacuum drawn through said suction holes, andwith its marginal edges overlying the marginal areas of said stockmaterial circumscribing said cut out; and a heated cylindrical rollrotatably supported with its cylindrical surface adjacent thecylindrical surface of said drum which carries said blank and saidpatch, so that the heated roll contacts only the overlapped marginaledge areas of said patch and said stock material circumscribing saidwindow cut out.